HIV Vaccines and ART Therapy

What is a Vaccine?
A vaccine is something that teaches the body to recognize and defend itself against viruses or bacteria that cause disease. Vaccines are designed to help people who are not yet infected, either by preventing infection or by slowing disease progression following future infection. A vaccine is not the same thing as a cure.

Effective vaccines have already been developed for some diseases, such as smallpox, polio and tetanus, and these have saved millions of lives. But there is still no vaccine against HIV, the virus that causes AIDS.
An AIDS vaccine could be effective in either of two ways.

A ”Therapeutic” vaccine would not stop infection, but would prevent HIV causing disease, and might also help prevent onward transmission.

Although a preventive vaccine would be ideal, a therapeutic vaccine would also have great value.

How do HIV vaccines work?
The basic idea behind all AIDS vaccines is to encourage the human immune system to fight HIV. The immune system works using a combination of cells and chemicals called antibodies. Early vaccine research focused on teaching the immune system to produce antibodies that would block HIV entering human cells. However, products designed to work this way failed in clinical trials, because the antibodies produced worked only against lab-cultured HIV, and not against the wild strains of virus. Today most research focuses on encouraging the immune system to produce cells to fight HIV. Nevertheless, many scientists believe such “cell–mediated” approaches will not be very effective on their own, even as therapeutic vaccines. It seems likely that a really effective vaccine will have to take a two–pronged approach involving both cells and antibodies.

Difficulties in developing HIV vaccines.
Developing a vaccine against HIV is a very difficult challenge for scientists. There are many reasons for this, including:

Nobody has ever recovered from HIV infection, so there is no natural mechanism to imitate.

HIV destroys the immune system cells that are meant to fight against it.

Soon after infection, HIV inserts its genetic material into human cells, where it remains hidden from the immune system.

HIV occurs in several subtypes , each of which is very different from the others

Even within each subtype, HIV is highly variable and constantly changing.

There are no good animal models with which to experiment.

Anti-retroviral Drugs Treatment.
This is the main type of treatment for HIV or AIDS. It is not a cure, but it can stop people from becoming ill for many years. The treatment consists of drugs that have to be taken every day for the rest of someone's life.

The antiretroviral HIV drugs that are currently available can improve the quality of life of someone infected with HIV, helping them to stay well much longer than they otherwise would. The drugs slow down the replication of HIV within the body, but it must be remembered that they are a treatment and not a cure.

The right time to start the treatment.
Deciding when to start treatment can be difficult as there is no proven ‘right' time. Still most guidelines recommend not starting treatment until the advanced stages of HIV infection. (stage-3 and stage-4)

Based on some factors the treatment should be started :

when the CD4 test shows between 200 to 350 T-helper cells per cubic millimeter of blood ( Advice varies slightly between countries.)

your viral load is medium or high.

If one of the opportunistic infections / illnesses has become a serious problem.

The anti-HIV drugs should reduce viral load to below the level of detection of the current tests, and the drugs should also boost CD4 levels.

Treatment coverage around the world

Region People receiving treatment in June 2006 People needing treatment in 2005 Treatment coverage in June 2006

Sub-Saharan Africa

1,040,000

4,600,000

23%

Latin America and the Caribbean

345,000

460,000

75%

East, South and South-East Asia

235,000

1,440,000

16%

Europe and Central Asia

24,000

190,000

13%

North Africa and the Middle East

4,000

75,000

5%

All developing and transitional countries

1,650,000

6,800,000

24%

As of June 2006, UNAIDS and the World Health Organization (WHO) estimate that 6,800,000 people in low- and middle-income countries were in need of antiretroviral (ARV) treatment for AIDS. Of these, only 24% were receiving it.

The Treatment and combination therapy. Antiretroviral treatment for HIV infection consists of drugs which work against HIV infection itself by slowing down the replication of HIV in the body. The drugs are often referred to as:

antiretrovirals

anti-HIV drugs

HIV antiviral drugs

For antiretroviral treatment to be effective for a long time, it has been found that you need to take more than one antiretroviral drug at a time. This is what is known as Combination Therapy. The term Highly Active Antiretroviral Therapy (HAART) is used to describe a combination of three or more anti–HIV drugs.

For most people, there are a number of drug combinations available to choose from. There are more than 20 approved drugs belonging to four different groups. It is not always easy to tell which will be the best option, since a combination that suits one person might not suit another.

When HIV replicates (makes new copies of itself) it often makes mistakes. This means that within any infected person there are many different strains of virus. Occasionally, a new strain is produced that happens to be resistant to the effects of an antiretroviral drug. If the person is not taking any other type of drug then the resistant strain is able to replicate quickly and the benefits of treatment are lost.

Taking two or more antiretrovirals at the same time vastly reduces the rate at which resistance develops.

ART drugs are becoming cheaper in India
The prices of first–line anti–retroviral therapy (ART) drugs, the only known treatment that suppresses the HIV virus and that was available to Indian patients till now, has dipped.

Till now, Naco paid Rs 7,000 to purchase drugs for every patient on treatment every year. Over 1.3 lakh HIV patients are on ART at present who get it free from any government–run ART centre.

According to the latest tender, announced and opened for bidding on December 5 and then finalized by Naco, a generic drug making Indian company will supply the same drugs for Rs 2,000 less.

India uses two–drug and three–drug combinations under the ART programme. Drugs like Stavudine, Lamivudine, Nevirapine, Efavirenz and Zidavudin are given in combination to decrease resistance among HIV positive patients. At present, seven Indian companies make generic first–line ART drugs. Naco spent Rs 60 crore on just procuring drugs in 2006.

Second–line ART therapy
India is all set to roll out second–line ART to over 3,000 HIV patients from January in two centres – Mumbai's J J Hospital and Chennai's Tambaram ART centre. These patients were facing imminent death because they had become resistant to the first-line treatment, thanks to poor adherence to the treatment regimen.

Second-line therapy is expensive – it will cost Naco Rs 8,000 per patient on ART per month. Clinton Foundation will provide the drugs for free to Naco for the next two years. The foundation will in turn get the drugs from UNITAID, an international drug purchasing facility.

Ten doctors from Delhi , Mumbai and Chennai have just returned from Thailand after being trained on operational issues relating to second-line therapy. They were taught the treatment protocols, and how to roll out and monitor the treatment lest patients become resistant.